Add XBitmap support (direct usage GIMP *.xbm files)

[subsonicpulse]

Draw XBitMap Files (*.xbm), exported from GIMP,
Usage:
Export from GIMP to *.xbm, rename *.xbm to *.c and open in editor.
C Array can be directly used with this function
void Adafruit_GFX::drawXBitmap(int16_t x, int16_t y,
const uint8_t *bitmap, int16_t w, int16_t h,
uint16_t color)

[subsonicpulse]

Tested with Adafruit_SSD1306. Picture from a In-Car project.

[ZaioBaio]

Very nice fix. Why it is not already merged to the master branch?

[tdicola]

Thanks for submitting the change and apologies it took a little while to be reviewed. Looks like a great change--thanks for adding some comments on the usage, etc. I tested it out and it works really well. Just merged in the change, thanks!

[griffdrummer]

Just as a heads up, to use the "drawXBitmap" function, I also had to redefine the array from "static unsigned char" to "static const uint8_t PROGMEM" in my image file. If I just used the original file, then garbage would appear on my 32x32 gird. I think the array has to be defined as "PROGMEM" because the "drawXBitmap" function uses the "pgm_read_byte" function, which reads a byte from program memory. I also had to include the line "#include <avr/pgmspace.h>". After that, everything worked fine for me.

[tdicola]

Oh yep, the function does assume the data is in flash memory by using the PROGMEM attribute. Thanks for digging in and commenting on what you found so other folks can learn from it too!

[svgeesus]

Hello griffdrummer,

Sunday, November 23, 2014, 10:58:55 PM, you wrote:

Just as a heads up, to use the "drawXBitmap" function, I also had
to redefine the array from "static unsigned char" to "static const
uint8_t PROGMEM" in my image file.

Ideally it would be const static unsigned uint8_t PROGMEM so that on
ARM processors (and on more recent compilers for AVR) it still works
and still gets put into Flash rather than SRAM.

Best regards,
Nantonos mailto:nantonos@epona.net

[seb155]

Hi,
I've try the drawXBitmap function, but it doesn't seem to work on a ARDUINO_ARCH_ARC32 (Arduino 101).
Result on the matrix seem to be random pixel.
I use a static const uint8_t PROGMEM:

// My bitmap exported by GIMP ".xbm"
static const uint8_t PROGMEM xbitmap [] = {
0x80, 0xff, 0x00, 0x70, 0x15, 0x03, 0x70, 0x02, 0x03, 0x88, 0x0a, 0x0c,
0x06, 0x05, 0x10, 0xa6, 0x14, 0x10, 0x46, 0x00, 0x10, 0x0b, 0xa0, 0x60,
0x13, 0x00, 0x75, 0x0b, 0x40, 0x65, 0x13, 0x00, 0x61, 0x13, 0x20, 0x60,
0x21, 0x40, 0x60, 0x43, 0x29, 0x60, 0x21, 0x52, 0x60, 0xd1, 0xff, 0x61,
0xe1, 0xff, 0x75, 0x3e, 0x23, 0x1e, 0x08, 0x22, 0x0c, 0x08, 0x22, 0x0c,
0x08, 0x00, 0x0c, 0x30, 0x00, 0x02, 0xc0, 0xdd, 0x01, 0xc0, 0xff, 0x01 };

// code
matrix.drawXBitmap(0, 0, xbitmap, 32, 24, 0xff);

If I use the drabitmap with the image2cpp converter "http://javl.github.io/image2cpp/"
Picture show up correctly on my led matrix.

Can it be a problem with the function "pgm_read_byte()" ??

[subsonicpulse]

Can you paste the xbm file content?
It seems it has not the right proportions. when i import it to GIMP then it needs to be 24x32 to get a mushroom picture. Otherwise its just snow. :-)
maybe you need to re-create it with the right aspect ratio